From Midland Manufacturing, a safer, stronger pressure relief valve

Midland Manufacturing of Skokie, Ill, a Dover Corp. company and supplier of valves and level-measurement devices for the rail tank car market since 1951, is among the equipment manufacturers on a CBR (crude by rail) tank car safety task force convened by the Railway Supply Institute Committee on Tank Cars (RSICTC), Association of American Railroads (AAR) Tank Car Committee, and various rail equipment manufacturers.

The task force’s main focus is the safety level of DOT-111 tank cars, 92,000 of which are used to move flammable liquids such as crude oil and ethanol. All DOT-111 tank cars ordered since October 2011, and built to transport crude oil, adhere to tougher CPC-1232 AAR Tank Car Committee standards. They are equipped with a thicker, more puncture-resistant shell or jacket, half-height protective head shields, additional protection for top fittings, and high flow pressure relief valves. In November 2013, the AAR offered additional, stricter recommendations designed to toughen federal safety standards, including an outer steel jacket around the tank car and thermal protection, full-height head shields, higher-flow-capacity pressure relief valves, and design modifications to prevent bottom outlets from opening during an accident.

RSI agreed that higher-flow-capacity pressure-relief devices that protect against over-pressurization of the tank car and reconfigured bottom outlet valve handles that ensure full containment in the event of a derailment be made standard equipment on all current and newly ordered tank cars that will be used to ship crude oil.

Midland has completed development of the A-22039 Smart-Flow™ Pressure Relief Valve (PRV), “recognizing the severity of the CBR safety issue, and knowing that a long-term solution needed to be found,” says Global Director Kevin Cook. “In analyzing the causes and effects of the recent CBR derailment incidents, the FRA’s Analysis of Fire Effects on Tank Cars (AFFTAC) Program determined existing PRV valves did not operate quickly enough and minimized the amount of time that first responders had to mitigate the situation.”

“In conjunction with the recommendations of railcar builders/owners, shippers, regulators, and first responders, Midland designed the A-22039 Smart-Flow dual stage PRV to be a next-generation PRV that will react in a predictable, controlled fashion during a tank car emergency, which will help minimize the chance of a high-energy event or explosion, Cook says. “The A-22039 is the railcar industry’s first two-stage, external, stainless-steel PRV. Whether an accident finds the railcar on its side or upright, the Smart-Flow technology ensures that pressure in the car is reduced to less than 4 psig (0.3 bar) before the tank fails due to fire.”

“The statistics show that rail is still one of the safest ways to transport hazardous or flammable materials, but as circumstances change, a whole new set of operational issues must be addressed in order to ensure that level of expected safety,” says Cook. “Improving CBR tank car safety is a front-of-mind concern for everyone in the rail industry and has brought together the brightest minds in a collaborative effort to craft a solution. Midland Manufacturing is proud of its 63-year commitment to providing the best equipment solutions to the railcar industry, and to being a contributor to this important initiative. Midland fully supports a comprehensive approach to new DOT-111 regulations that will improve tank car safety for the transporting of crude oil.”